Oilfield production equipment often requires pressure compensation to compensate fluid volumes within the system. There are many ways to compensate two fluid volumes, including but not limited to compensating pistons and axial bellows. Compensating pistons and axial bellows work well for fluid volumes that are offset axially but are not suitable to compensate fluid volumes that are concentric. Current technologies often require the use of a sealing element which may not be reliable in permanent oilfield downhole equipment.
Bellows have been used in motor protectors. U.S. Pat. No. 7,217,107 illustrates a motor protector comprising a bellow assembly for isolating the internal fluid of a submersible pumping system. Bellows have been used for expansion joints to compensate for thermally induced forces. U.S. Pat. No. 4,332,401 illustrates an expansion joint for casing used in injecting steam into wells. U.S. Pat. No. 5,421,241 and U.S. Pat. No. 6,932,581 both illustrate the use of bellows in gas lift valve systems. U.S. Pat. No. 5,143,158 illustrates the use of bellows in a subsea wellhead apparatus.